Radiotelephones typically include a main body having a speaker housed in the upper portion thereof and oriented to direct sound directly through an outer housing into the user's ear. The overall quality of speech and sound emitted by the. speaker of a radiotelephone is sometimes referred to as speech intelligibility. Speech intelligibility in radiotelephones is generally affected by a number of design factors including the speaker design, how the speaker is housed, and how the emitted sound energy is channeled to the ear. Ideally, a radiotelephone should produce a fairly level frequency response for a frequency range of approximately 300 Hz to 3,000 Hz. In practice and with an unsealed ear, some radiotelephone designs experience a frequency response drop-off of about 12 db per octave starting at about 1,000 Hz and continuing towards the lower end of the frequency response scale. Thus, speech and sound associated with these lower frequencies is not transmitted clearly and distinctly. Consequently, the intelligibility of the transmitted speech and sound is often poor.
Moreover, almost universally, speakers are placed in the same relative positions in radiotelephones, that is near the top of the main body and situated to direct sound through the front of the housing. This enables users to create a sealed or near sealed relationship between the speaker and the ear. However, by consistently adhering to the thinking that the speaker can only be appropriately positioned in one location within the radiotelephone, overall design flexibility is certainly restricted.